Predictions for Chemistry 2014 HSC? (1 Viewer)

[iStudent]

shouldn't you guys be in school?

Nope.

 

[seventhroot]

Nope.

k den

nvm

 

[xenophanes]

Lead Acid cells are rechargeable

Yes but it got lead in it.

 

[enigma_1]

Yes but it got lead in it.

and sulphate

 

[xenophanes]

When was the last time they asked for a named chemist and their role?

 

[SuchSmallHands]

Describe the nebulisation of the prepared solution and explain the need for the flame in AAS (3)

I'm a bit dodgy on AAS, but I'll give it a go.
Nebulisation: converts the sample to a fine spray which enters the flame
Flame: the flame desolvates the 'wet' aerosol and thermally decomposes the ionic compound containing the metal ions to be tested for into ground state atoms which can absorb light of the frequency emitted by the elemental metal sample in the hollow cathode lamp to reach an excited state.

 

[SuchSmallHands]

Nothing for 5 hours then all of that in a couple of minutes haha

 

[faisalabdul16]

I don't get what you guys are on about?
A lead-acid cell is rechargeable.

 

[enigma_1]

I don't get what you guys are on about?
A lead-acid cell is rechargeable.

iStudent asked for the environmental problems with dry cell specifically though

State one environmental impact associated with the dry cell (1mk). This is a hsc q but I'm forcing you to choose dry over lead acid.

 

[xenophanes]

I'm a bit dodgy on AAS, but I'll give it a go.
Nebulisation: converts the sample to a fine spray which enters the flame
Flame: the flame desolvates the 'wet' aerosol and thermally decomposes the ionic compound containing the metal ions to be tested for into ground state atoms which can absorb light of the frequency emitted by the elemental metal sample in the hollow cathode lamp to reach an excited state.

Is there another word for nebulisation cos I swear I have never heard that word b4..

 

[enigma_1]

Is there another word for nebulisation cos I swear I have never heard that word b4..

I usually think of it as the flame atomises the sample (making it into a vapour). But yeah I don't use nebulisation usually. I'd probably chuck it in though so the marker doesn't take off marks

 

[faisalabdul16]

I haven't heard of the word nebulisation as well

 

[GOsie]

The more I read this thread, the more I realise how little I know

 

[enigma_1]

Discuss the use of the suitable chemical to minimise acid or base spill. Use appropriate eqns. -5

_/_/_

someone ^

 

[QZP]

Nebulisation: Converts prepared solution into fine "mist" whilst mixing with a fuel. This mist is then fed into the flame
Flame: Required to convert metal ions to free atoms where they can thus absorb incoming light from cathode lamp

 

[GOsie]

Discuss the use of the suitable chemical to minimise acid or base spill. Use appropriate eqns. -5

_/_/_

When cleaning the spill of an unknown liquid (either acidic or basic), it is important to carefully chose a suitable chemical in order to minimise any damage. One such chemical that may be used is Sodium Hydrogen Carbonate (NaHCO3). This chemical is particularly useful in cleaning spills of acids and bases for multiple reasons.

Its ion HCO3- is amphiprotic, meaning it can donate or accept a proton, which is ideal for when the nature (acidity or basicity) of the spill is unknown, as it can neutralise either.

With the spill of the acid HCl
HCl + NaHCO3 <-> H2O + CO2 + NaCl

And in the spill of the base NaOH
NaHCO3 + NaOH <-> Na2CO3 +H2O

as seen in the above equations NaHCO3 neutralises both acids and bases.

NaHCO3 is a solid chemical, and can thus be contained easily.

It is non-toxic, and is thus safe to handle in school labs

Thus it can be seen that NaHCO3 is a suitable chemical to clean up acid and base spills



Is this even close to right?

 

[SuchSmallHands]

When was the last time they asked for a named chemist and their role?

I think this in 2007
Describe the role of a chemist employed in an industry or enterprise, and a chemical principle used by the chemist. (Choose an occupation other than teaching.)
Was the last time they asked anything like that. But note that it doesn't require you to name a particular chemist, just outline the role of a chemist.

 

[SuchSmallHands]

I usually think of it as the flame atomises the sample (making it into a vapour). But yeah I don't use nebulisation usually. I'd probably chuck it in though so the marker doesn't take off marks

Yeah to be honest nebuliser is more reminiscent of that asthma machine thing that what I'd normally say atomiser for me personally. But be careful with wording there, because the flame doesn't atomise the sample, the atomiser/nebuliser does; it enters the flame already atomised (and then is made into atoms, and I guess it's the similarity between those words that make it easier for some people to remember nebuliser instead).

 

[Hi there444]

State one environmental impact associated with the dry cell (1mk). This is a hsc q but I'm forcing you to choose dry over lead acid.

Weak Ammonium Chlroide solution is corrosive and can be damaging to environment.

 

[enigma_1]

Yeah to be honest nebuliser is more reminiscent of that asthma machine thing that what I'd normally say atomiser for me personally. But be careful with wording there, because the flame doesn't atomise the sample, the atomiser/nebuliser does; it enters the flame already atomised (and then is made into atoms, and I guess it's the similarity between those words that make it easier for some people to remember nebuliser instead).

oh wow I didn't know that part. Thanks for clearing it up!